Has your little bowl of flour and water been sitting for 2 to 3 (or maybe 4 or 5) days? Seeing those bubbles yet? Has your starter formed a nice little crusty upper shell? The “crust” isn’t required, it just kind of happens when air meets flour combined with water.

Once you see a good amount of activity (aka bubbles) when you look through the glass bowl, congrats! You’ve harnessed wild yeasts (and bacteria), and now it’s time to start training them so you can ride them off into the sunset use them to make unbelievable bread.

Once you peel back the hardened, upper layer, you’ll see the bubbly texture that has formed underneath.

This training period is a feeding of your starter and it will allow the community of bacteria and yeast that provide the flavor and rise of sourdough to become stable and reliable. As Chad Robertson says in his book Tartine Bread (from which we are drawing this entire edition of Sourdough Starter School) this is the time to pay attention to how your sourdough changes throughout the fermentation process. Give it a good sniff before and after feeding. What has changed? When do you see the most bubbles? Do you notice a difference in appearance, smell or consistency when the temperature in your home shifts? Give a little attention to all of these things, and you’ll begin to develop a sense of when your starter has stabilized and when it’s ready to use as actual leaven for bread. We’ll discuss both of those over the next 3 days of Sourdough Starter School, but for now, let’s get feeding.